The goal of this project is to identify and analyze the cellular functions which are required specifically for meiosis in the yeast, Saccharomyces cerevisiae. In particular, we are focusing on the analysis of the SPO11 gene of yeast which is required for recombination and proper chromosome segregation during meiosis. A general system has been developed to isolate meiosis specific genes of yeast for which mutants are available. Using this system, the SPO11+ wild type gene has been isolated following transformation and complementation of a spo11-1 mutant with a total genome clone bank. The function of the cloned gene has been examined during a detailed analysis of the complementation of the spo11-1 mutant by the isolated SPO11+ gene. The structure of the cloned gene has been partially determined by restriction enzyme analysis; it is being further analyzed by fine structure restriction analysis and by subcloning. The DNA sequence of the cloned SPO11+ gene will be determined. The function of the cloned gene will be further characterized by mutagenesis of the cloned DNA and by substitution of the chromosomal SPO11+ gene by in vitro engineered constructions. We will try to identify the gene product of the SPO11+ gene by expression of the cloned gene in an E. coli system.